// Start training from the collected faces.
        // The face recognition algorithm can be one of these and perhaps more, depending on your version of OpenCV, which must be atleast v2.4.1:
        //    "FaceRecognizer.Eigenfaces":  Eigenfaces, also referred to as PCA (Turk and Pentland, 1991).
        //    "FaceRecognizer.Fisherfaces": Fisherfaces, also referred to as LDA (Belhumeur et al, 1997).
        //    "FaceRecognizer.LBPH":        Local Binary Pattern Histograms (Ahonen et al, 2006).
        public static BasicFaceRecognizer LearnCollectedFaces(List <Mat> preprocessedFaces, List <int> faceLabels, string facerecAlgorithm = "FaceRecognizer.Eigenfaces")
        {
            BasicFaceRecognizer model = null;

            Debug.Log("Learning the collected faces using the [" + facerecAlgorithm + "] algorithm ...");

            if (facerecAlgorithm == "FaceRecognizer.Fisherfaces")
            {
                model = FisherFaceRecognizer.create();
            }
            else if (facerecAlgorithm == "FaceRecognizer.Eigenfaces")
            {
                model = EigenFaceRecognizer.create();
            }

            if (model == null)
            {
                Debug.LogError("ERROR: The FaceRecognizer algorithm [" + facerecAlgorithm + "] is not available in your version of OpenCV. Please update to OpenCV v2.4.1 or newer.");
                //exit(1);
            }

            // Do the actual training from the collected faces. Might take several seconds or minutes depending on input!
            MatOfInt labels = new MatOfInt();

            labels.fromList(faceLabels);
            model.train(preprocessedFaces, labels);

            return(model);
        }
        private void Run()
        {
            List <Mat> images     = new List <Mat> ();
            List <int> labelsList = new List <int> ();
            MatOfInt   labels     = new MatOfInt();

            images.Add(Imgcodecs.imread(image_0_filepath, 0));
            images.Add(Imgcodecs.imread(image_1_filepath, 0));
            labelsList.Add(0);
            labelsList.Add(1);
            labels.fromList(labelsList);

            Mat testSampleMat   = Imgcodecs.imread(sample_image_filepath, 0);
            int testSampleLabel = 0;


            //                      foreach (Mat item in images) {
            //                              Debug.Log ("images.ToString " + item.ToString ());
            //                      }
            //                      foreach (int item in labelsList) {
            //                              Debug.Log ("labels.ToString " + item.ToString ());
            //                      }

            int[]    predictedLabel      = new int[1];
            double[] predictedConfidence = new double[1];


            BasicFaceRecognizer faceRecognizer = EigenFaceRecognizer.create();

            faceRecognizer.train(images, labels);

            faceRecognizer.predict(testSampleMat, predictedLabel, predictedConfidence);


            Debug.Log("Predicted class: " + predictedLabel [0] + " / " + "Actual class: " + testSampleLabel);
            Debug.Log("Confidence: " + predictedConfidence [0]);


            Mat predictedMat = images [predictedLabel [0]];

            Mat baseMat = new Mat(testSampleMat.rows(), predictedMat.cols() + testSampleMat.cols(), CvType.CV_8UC1);

            predictedMat.copyTo(baseMat.submat(new OpenCVForUnity.CoreModule.Rect(0, 0, predictedMat.cols(), predictedMat.rows())));
            testSampleMat.copyTo(baseMat.submat(new OpenCVForUnity.CoreModule.Rect(predictedMat.cols(), 0, testSampleMat.cols(), testSampleMat.rows())));

            Imgproc.putText(baseMat, "Predicted", new Point(10, 15), Imgproc.FONT_HERSHEY_SIMPLEX, 0.4, new Scalar(255), 1, Imgproc.LINE_AA, false);
            Imgproc.putText(baseMat, "Confidence:", new Point(5, 25), Imgproc.FONT_HERSHEY_SIMPLEX, 0.2, new Scalar(255), 1, Imgproc.LINE_AA, false);
            Imgproc.putText(baseMat, "   " + predictedConfidence [0], new Point(5, 33), Imgproc.FONT_HERSHEY_SIMPLEX, 0.2, new Scalar(255), 1, Imgproc.LINE_AA, false);
            Imgproc.putText(baseMat, "TestSample", new Point(predictedMat.cols() + 10, 15), Imgproc.FONT_HERSHEY_SIMPLEX, 0.4, new Scalar(255), 1, Imgproc.LINE_AA, false);


            Texture2D texture = new Texture2D(baseMat.cols(), baseMat.rows(), TextureFormat.RGBA32, false);

            Utils.matToTexture2D(baseMat, texture);

            gameObject.GetComponent <Renderer> ().material.mainTexture = texture;
        }